Merge pull request #63 from fedora-infra/global_notif

Global notif
Let PackageListingAcl.get_pending_acl return all pending ACLs requests if not user is specified
Let get_pending_acl_user return all pending ACLs requests if not user is specified
Add a new extra API endpoint listing all the pending ACL requests
Add unit-tests for the new API endpoint listing the pending ACL requests
List the /api/pendingacls in the API documentation
More tests for /api/pendingacls in json restricted with a username that has no pending ACLs